1. Field of the Invention
The present invention relates to communications networks and, more specifically, to restoration time improvements in (e.g., optical) mesh networks.
2. Description of the Related Art
In robust communications networks, it is typical to provide path redundancy for services. This is generally done by providing a primary path and a restoration path for each service. In the event of a failure along the primary path, the service traffic is switched over to the restoration path. Note that, in the art, the term “primary path” is often synonymous with the term “working path,” while the term “restoration path” is often synonymous with the terms “protection path” and “alternative path.”
For optical mesh transport networks, a challenge is to provide cost-effective systems that support restoration times that are comparable to those provided by SONET/SDH networks with self-healing rings (e.g., 10-100 ms restoration times). To help reduce network restoration time in optical mesh networks, several areas have been considered, including improving restoration signaling and associated algorithms and improving the switching speed of cross-connection infrastructure switching elements. A critical bottleneck for restoration speedup is the maximum number of cross-connections to be performed at a single network element in the event of a failure. Assuming everything else is constant, the larger the number of cross-connects, the longer the restoration time.